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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28108 results found.

  1. GRB 250905A: KAIT optical upper limit
  2. GRB 250905A: Swift detection of a burst
  3. GRB 250904A: Enhanced Swift-XRT position
  4. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 250904A: TRT optical counterpart detection
  6. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  7. GRB 250904A: Swift detection of a burst
  8. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  9. GRB 250902A: VZLUSAT-2 detection
  10. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  11. GRB 250903A: Swift-XRT observations
  12. EP250903a: Swift-XRT observations
  13. EP#01709201209: Swift-XRT observations
  14. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  15. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  16. GRB 250830C: VZLUSAT-2 detection
  17. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  18. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  20. GRB 250903A: EP-FXT counterpart detection
  21. GRB 250902A: GECAM-B detection
  22. GRB 250903A: LCO optical observation
  23. GRB 250903A: LCO optical afterglow detection
  24. GRB 250903A: SVOM/VT optical confirmation with VHF data
  25. EP250901a: Mondy, Assy and SAO RAS optical limits
  26. EP250903a: LCO candidate counterpart discovery
  27. GRB 250903A: TRT optical counterpart detection
  28. EP250903a: TRT optical observations
  29. EP250903a: Einstein Probe detection of an X-ray transient
  30. EP 250827B: Detection of supernova counterpart by LCO.
  31. GRB 250902B: SVOM/GRM observation
  32. EP250827b: SVOM/VT observation of AT 2025wkm
  33. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  34. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  35. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  36. GRB 250902A: Fermi GBM Detection
  37. GRB 250901A: Swift/UVOT Upper Limit
  38. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 250830B: Swift-XRT afterglow detection
  40. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  41. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  42. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  43. GRB 250902A: SVOM/GRM observation
  44. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  45. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  46. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 250901A: SVOM/VT optical afterglow with VHF data
  48. GRB 250901A: Swift-XRT afterglow detection
  49. EP250901a: Swift-XRT observations
  50. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  51. GRB 250901A: LCO optical upper limit
  52. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  53. EP250827b: Gemini Spectroscopy of AT 2025wkm
  54. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  55. EP250831a: NOT optical observations and tentative afterglow candidate
  56. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  57. GRB 250901A: SVOM detection of a burst
  58. EP250901a: Mephisto optical upper limits
  59. GRB 250830C: GECAM-B detection
  60. EP250901a: Einstein Probe detection of an X-ray transient
  61. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  62. EP250831a: Swift-XRT observations
  63. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  64. EP250831a: EP-WXT detection of a fast X-ray transient
  65. GRB 250831A: Swift-XRT counterpart detection
  66. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. GRB 250831A: SVOM/VT upper limit with VHF data
  68. GRB 250831A: SVOM detection of a soft burst
  69. GRB 250830B: Swift-XRT observations
  70. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  71. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  72. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  73. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  74. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  75. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  76. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  77. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  78. GRB 250830B: MAXI/GSC detection
  79. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  80. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  81. GRB 250828B: Swift-BAT refined analysis
  82. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  83. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  84. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  85. EP250828a: Optical counterpart detection with Kinder observations
  86. EP250828a: Liverpool Telescope upper limits
  87. EP250828a: Global MASTER-Net observations report
  88. EP-WXT trigger 01709200800 : KAIT optical observations
  89. EP250828a: KAIT optical upper limit
  90. EP250827a: Swift/UVOT Detection
  91. EP250828a: NOT optical counterpart confirmation
  92. EP250828a: SVOM/VT optical candidate
  93. EP250828a: Seimei/TriCCS optical counterpart detection
  94. EP250828a: Optical upper limit with Kinder observations
  95. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  96. EP250827a: LCO observations show fading optical counterpart
  97. EP250828a: Einstein Probe detection of an X-ray transient
  98. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  99. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  100. EP250827a: confirmation of optical rebrightening with LCO

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